Recent research shows sedentary work increases the risk of cancer and heart disease regardless of other health indicators such as exercise and nutrition. However, standing all day in a static position can also cause health problems, including a significant increase in the risk of carotid atherosclerosis. The healthiest workplace solution allows users to alternate between sitting and standing positions throughout the day.
Height adjustable tables have been developed to allow a user to change posture from a seated to a standing position throughout the day. Height adjustable tables are ideally construed to have task specific heights that are ergonomically correct. An ergonomically correct position is one where the height of the work surface of a table is at the user's elbows and where the height of the work surface provides adequate leg room and knee space allowing a user to feel uncrowded and to allow for some changes of position. Existing height adjustable tables typically utilize either a hand crank, an electric motor, or a counterbalance mechanism to adjust the height of the work surface.
Counterbalance adjustable tables, which utilize either a counterweight or a spring to offset the load on the work surface, are advantageous over hand crank tables and electric tables since the height of the work surface can be effortlessly adjusted without consuming electricity. However, the counterbalance assemblies are typically disposed either within the table's leg(s) or within a cross-member beam extending between table's legs. For instance, U.S. Pat. No. 7,658,359 discloses a single leg counterbalance table having a compression spring disposed within a pedestal-type support leg extending below the work surface. Meanwhile, U.S. Pat. No. 5,706,739 discloses a multi-leg counterbalance table having a torsion spring disposed within a cross-member beam extending between the table's legs. Disadvantageously, both arrangements cause the table's support structure to be bulky, thereby reducing leg room below the work surface.
Previous attempts have been made to develop a height adjustable table, having a less bulky counterbalance mechanism, which does not restrict leg room below the work surface. For instance, another known height adjustable table features a counterbalance mechanism comprising gas springs disposed within opposing table legs, with each gas spring designed to provide a preset counterbalance force. While such a table provides for more leg room by eliminating the bulky cross-member beam, the counterbalance mechanism does not accommodate for varying loads. If the load on the work surface exceeds the counterbalance force, adjustment of the table's work surface may require the user to exert an excessive amount of force. Conversely, if the counterbalance force exceeds the applied load, the work surface may surprisingly move rapidly and thus present a safety hazard.